Filter For Smoking or Vaping Article Comprising a Nonwoven Substrate

ABSTRACT

The present invention relates to a filter comprising a nonwoven substrate having a low density and comprising natural fibers and a binder. The filter can be used as a filter for a smoking or vaping article.

TECHNICAL FIELD

A subject of the invention is a filter comprising a nonwoven substratehaving a low density and comprising natural fibers and a binder. Thisnonwoven substrate is capable of being obtained by a drylaid process.This filter can be used as filter for a smoking or vaping article.

PRIOR ART

A filter for a smoking or vaping article has a right circularcylindrical shape and generally comprises an outer envelope of plug wrappaper and a substrate located within the outer envelope. The filter fora smoking or vaping article, by virtue of the substrate, makes itpossible to prevent the user from inhaling tobacco particles and allowsretention of the harmful particulate substances contained in the smokeor the aerosol, such as tar.

Filters are commonly made from cellulose acetate. These celluloseacetate filters have a nicotine retention capacity such that the user'sperception of the filtered smoke is satisfactory. In addition, thesefilters generate a filtered smoke having good organoleptic properties.However, these cellulose acetate substrates degrade very slowly and arenot dispersible in water. This is particularly harmful since the filteris not consumed during the smoking/vaping of a smoking/vaping articleand is regularly found in the environment. Cellulose acetate substratesthus have a significant environmental impact.

To limit the environmental impact of conventional filters, it has beenproposed to replace the cellulose acetate with paper. As papersubstrates are biodegradable, they degrade rapidly. However, thenicotine retention capacity of filters comprising a paper substrate issuch that the user's perception of the filtered smoke may not besatisfactory. In addition, the smoke filtered by filters comprising apaper substrate may have a drying taste which is unsatisfactory for theuser. The user experience provided by these paper substrates is thus notas satisfactory when compared with cellulose acetate.

Technical Problem

There is therefore a need for a filter which has a nicotine retentioncapacity of the same order of magnitude as that of a filter comprising acellulose acetate substrate, which provides a satisfactory userexperience.

It is thus to the credit of the inventors to have found that it waspossible to meet this need by means of a nonwoven substrate.

SUMMARY

It is proposed a filter comprising a nonwoven substrate comprisingnatural fibers and a binder, in which the natural fibers representbetween 70% and 99%, in particular between 80% and 98%, veryparticularly between 85% and 98% by weight of solids of said nonwovensubstrate, the binder represents between 1% and 30%, in particularbetween 2% and 20%, very particularly between 2% and 15% by weight ofsolids of said nonwoven substrate, and characterized in that thenonwoven substrate has a density of between 7 mg/cm³ and 60 mg/cm³, inparticular between 8 mg/cm³ and 50 mg/cm³, very particularly between 10mg/cm³ and 40 mg/cm³.

Advantageously, the filter of the invention has a nicotine retentioncapacity of the same order of magnitude as the retention capacities of afilter comprising a cellulose acetate substrate. Consequently, theuser's perception of the smoke filtered by the filter of the inventionis satisfactory.

Moreover, the smoke filtered by the filter of the invention hasorganoleptic properties which are satisfactory for the user.

The nonwoven substrate can also make it possible to produce the filterof the invention without a prior shaping step, which is not the case forpaper substrates. Thus, the process for producing the filter of theinvention is simplified.

According to another aspect, a process is proposed for producing thefilter of the invention comprising a nonwoven substrate, said processcomprising the following steps:

-   -   a) forming a rod of nonwoven substrate from a nonwoven        substrate,    -   b) wrapping the rod of nonwoven substrate with a sheet of plug        wrap paper,    -   c) depositing an adhesive line, joining the sheet of plug wrap        paper to obtain a rod of filtering material,    -   d) cutting the rod of filtering material to produce the filter.        wherein the nonwoven substrate is as defined above or is        obtained by a process comprising the following steps:    -   i) producing a web from natural fibers by a drylaid process,    -   ii) introducing the binder into the web, and    -   iii) drying the web resulting from step ii) to obtain the        nonwoven substrate.

DESCRIPTION OF THE EMBODIMENTS

It is proposed a filter comprising a nonwoven substrate comprisingnatural fibers and a binder, in which the natural fibers representbetween 70% and 99%, in particular between 80% and 98%, veryparticularly between 85% and 98% by weight of solids of said nonwovensubstrate, the binder represents between 1% and 30%, in particularbetween 2% and 20%, very particularly between 2% and 15% by weight ofsolids of said nonwoven substrate;

characterized in that the nonwoven substrate has a density of between 7mg/cm³ and 60 mg/cm³, in particular between 8 mg/cm³ and 50 mg/cm³, veryparticularly between 10 mg/cm³ and 40 mg/cm³.

Compared to the conventional density of paper substrates, which isgreater than 300 mg/cm³, the density of the nonwoven substrate is verylow.

Without wishing to be bound by any theory, the inventors are of theopinion that, by virtue of this low density, the nonwoven substrate ofthe filter of the invention has a higher filter filling power than thefilling power of a paper substrate. This higher filling power makes itpossible to reduce the amount of nonwoven substrate present in thefilter such that the filter of the invention has a nicotine retentioncapacity of the same order of magnitude as the retention capacity of afilter comprising a cellulose acetate substrate.

For the purposes of the present application, “nonwoven substrate” (alsoreferred to as “non-woven substrate”) denotes a manufactured sheetconsisting of a web or ply of directionally or randomly oriented fibersbonded together by friction and/or cohesion and/or adhesion.

Typically, the density of the nonwoven substrate is calculated bydividing its grammage by its thickness.

The standard ISO 536:2012 can be used to determine the grammage of thenonwoven substrate. The substrate is conditioned for at least 16 hoursat 23° C. and 50% humidity before the measurement.

To measure the thickness of the nonwoven substrate, it is possible touse a dead-weight micrometer comprising a 25 cm² measuring head with twoplanar, parallel and circular pressure surfaces. During the measurement,the nonwoven substrate is placed between the two pressure surfaces for10 seconds. The pressure exerted between the pressure surfaces duringthe measurement of the thickness is 0.5 kPa. The substrate isconditioned for at least 16 hours at 23° C. and 50% humidity before themeasurement.

The grammage of the nonwoven substrate of the filter of the inventioncan for example be between 20 g/m² and 60 g/m², in particular between 23g/m² and 57 g/m², more particularly between 25 g/m² and 55 g/m².

The thickness of the nonwoven substrate of the filter of the inventioncan for example be between 700 μm and 6000 μm, in particular between1000 μm and 4700 μm, more particularly between 2000 μm and 4500 μm.

According to one particular embodiment, the nonwoven substrate can havea density of between 10 mg/cm³ and 40 mg/cm³, and a thickness of between2000 μm and 4500 μm.

The person skilled in the art will know how to adapt the grammage andthe thickness of the nonwoven substrate in order to achieve the desireddensity.

For the purposes of the present application, the term “natural fiber”denotes a fiber of natural origin which has optionally undergone achemical treatment, a physical treatment, or both, in order to optimizethe physical characteristics thereof.

For example, the natural fibers can be chosen from wood fibers, leaffibers, fruit fibers, seed fibers, bast fibers, stalk fibers, reedfibers, and mixtures thereof, in particular wood fibers, leaf fibers,seed fibers, bast fibers, and mixtures thereof, more particularly woodfibers, bast fibers and mixtures thereof.

Examples of wood fibers which may be present in the nonwoven substrateof the filter of the invention can be lyocell fibers (cellulose fiberswhich are ground and dissolved in N-methylmorpholine N-oxide monohydratefor the purpose of obtaining fibers with a cross section of variableshape (round, oval, cross-shaped, circular, lamellar cross section) withcalibrated length and mass per unit length, which the person skilled inthe art can choose depending on their needs), viscose fibers (fibersobtained by dissolving cellulose by means of modification of itshydroxyl groups by carbon disulfide (CS₂) and then its precipitation inthe presence of sulfuric acid (H₂SO₄) for the purpose of obtainingfibers with a cross section of variable shape (round, oval,cross-shaped, circular, lamellar cross section) with calibrated lengthand mass per unit length, which the person skilled in the art can choosedepending on their needs), and mixtures thereof, in particular lyocellfibers, viscose fibers, and mixtures thereof.

For the purposes of the present application, “bast fiber” denotes aplant fiber contained in the bast of the plants.

As bast fiber, mention may be made of hemp fiber, Indian hemp fiber,jute fiber, kenaf fiber, kudzu fiber, flax fiber, okra fiber, nettlefiber, ramie fiber, and mixtures thereof, in particular hemp fiber, flaxfiber, and a mixture thereof, more particularly flax fiber.

Typically, the bast fibers may have undergone prior treatment. Thus, thebast fibers may be cottonized bast fibers, individualized bast fibers,bast fibers which have undergone retting, bleached bast fibers, andmixtures thereof, in particular cottonized bast fibers, individualizedbast fibers and a mixture thereof.

For the purposes of the present application, “seed fiber” denotes afiber obtained from seeds of a plant. Examples of seed fibers can becotton fiber, kapok fiber, luffa fiber, milkweed fiber, and mixturesthereof, in particular kapok fiber.

According to one particular embodiment, the natural fibers are chosenfrom lyocell fibers, flax fibers, cottonized flax fibers, cotton fiberand mixtures thereof, in particular a mixture of cottonized flax fibersand lyocell fibers.

According to one particular embodiment, the natural fibers of thenonwoven substrate can be a mixture of natural fibers comprisingcottonized flax fibers and lyocell fibers,

the cottonized flax fibers represent more than 50%, in particularbetween 70% and 98%, more particularly between 85% and 95% by weight ofsolids of said mixture of fibers, and

the lyocell fibers representing less than 50%, in particular between 2%and 30%, more particularly between 5% and 15% by weight of solids ofsaid mixture of fibers.

According to the invention, the natural fibers, before use in thenonwoven substrate, can have a length of between 10 mm and 150 mm, inparticular between 15 mm and 100 mm, more particularly between 20 mm and60 mm.

A drylaid process is particularly suitable for this size of naturalfibers. Thus, the nonwoven substrate of the filter of the invention ofthis alternative embodiment can be obtained by a drylaid process.

The length of the natural fibers can be measured by a ClassifiberKCF-V/LS apparatus from Keisokki. Natural fibers are combed andindividualized before measurement. The sizes of the fibers are measuredautomatically by an optical method.

The natural fibers may also be cut so as to have a length within theranges mentioned above. Conventional cutting techniques which can beused are guillotine cutting of natural fibers, grinding of the naturalfibers with or without a system for removing excessively short andexcessively long fibers of air cyclone or screen type.

For the purposes of the present application, “binder” denotes a compoundhaving properties enabling consolidation of the nonwoven substrate.

For example, the binder can be a natural polymer, a synthetic polymer orcopolymer or a mixture thereof. The natural polymer can be apolysaccharide, a cellulose derivative, or a mixture thereof. Thesynthetic polymer can be a latex.

The polysaccharide which can be used as binder can be a polysaccharideor a polysaccharide derivative. For example, starch, dextrin, gumarabic, and mixtures thereof can be used as binder, in particularstarch.

For example, the cellulose derivative can be chosen from ethylcellulose, methyl cellulose, hydroxymethyl cellulose, hydroxyethylcellulose, carboxymethyl cellulose, an alkali metal salt ofcarboxymethyl cellulose, and mixtures thereof, in particularcarboxymethyl cellulose.

As alkali metal of the carboxymethyl cellulose salt, mention may be madeof potassium, sodium, and magnesium.

The synthetic polymer or copolymer can, for example, be a polyvinylalcohol, an ethylene-vinyl alcohol, a polyvinyl acetate, a polyvinylchloride, a styrene-butadiene, a polybutadiene, polyacrylics, anethylene-vinyl acetate, and mixtures thereof, in particular polyvinylalcohol.

According to another very particular embodiment, the nonwoven substratecan comprise:

a mixture of fibers comprising between 85% and 95% of cottonized flaxfibers by weight of solids of said mixture of fibers and between 5% and15% of lyocell fibers by weight of solids of said mixture of fibers, and

a binder chosen from starch, polyvinyl alcohol, ethylene-vinyl acetate,which can represent between 2% and 15%, in particular between 2% and 8%by weight of solids of said nonwoven substrate,

in which the mixture of fibers can represent between 85% and 98%, inparticular between 92% and 98% by weight of solids of said nonwovensubstrate; and

can have a density of between 10 mg/cm³ and 40 mg/cm³.

The nonwoven substrate of this other very particular embodiment can beobtained by a drylaid process.

The filter of the invention can be a filter for a smoking or vapingarticle.

For the purposes of the present application, “smoking article” denotesan article comprising tobacco and/or any other plant intended to besmoked. For example, the smoking article may be a machine-manufacturedcigarette, a roll-your-own cigarette or a make-your-own cigarette.

Typically, the filter for a smoking article has a right circularcylindrical shape and comprises an outer envelope of plug wrap paper fora smoking article, in particular for a cigarette, and the nonwovensubstrate of the filter of the invention as defined above located withinthe outer envelope.

For the purposes of the present application, “vaping article” denotes anarticle comprising tobacco and/or any other plant intended to be vaped,which is intended to be inserted into a device which heats the tobaccoand/or the plant without burning said tobacco/plant and which enablesdelivery of an aerosol to a user. For example, the vaping article can bea tobacco stick.

Typically, the filter for a vaping article has a right circularcylindrical shape and comprises an outer envelope of plug wrap paper fora vaping article, in particular for a tobacco stick, and the nonwovensubstrate of the filter of the invention as defined above located withinthe outer envelope.

The filter of the invention can have a density of between 100 mg/cm³ and200 mg/cm³, in particular between 110 mg/cm³ and 170 mg/cm³, moreparticularly between 115 mg/cm³ and 160 mg/cm³.

Typically, the density of the filter is measured after manufacture ofthe filters, by dividing the mass of the filter by its volume. For afilter having a right circular cylindrical shape, the volume of thefilter (Vater) is calculated by the following formula:V_(filter)=π*L*r², in which r denotes the radius of the filter and Ldenotes the length of the filter.

The nonwoven substrate of the filter of the invention may not be crimpedbefore the formation of the filter. This is highly advantageous since itmakes it possible to produce a filter while simplifying the productionof the filter.

According to another aspect, the present invention also relates to asmoking article comprising a filter as defined above.

According to another aspect, the present invention also relates to avaping article comprising a filter as defined above.

The present invention also relates to the use of a nonwoven substrate asdefined above in a filter, in particular a filter for a smoking articleor a filter for a vaping article.

The present invention also relates to a process for producing a filterfor a smoking or vaping article comprising a nonwoven substrate, saidprocess comprising the following steps:

-   -   a) forming a rod of nonwoven substrate from a nonwoven        substrate,    -   b) wrapping the rod of nonwoven substrate with a sheet of plug        wrap paper,    -   c) depositing an adhesive line, joining the sheet of plug wrap        paper to obtain a rod of filtering material,    -   d) cutting the rod of filtering material to produce the filter.        wherein the nonwoven substrate is as defined above or is        obtained by a process comprising the following steps:    -   i) producing a web from natural fibers by a drylaid process, and    -   ii) introducing the binder into the web,    -   iii) drying the web resulting from step ii) to obtain the        nonwoven substrate.

The nonwoven substrate, the natural fibers and the binder are asdescribed above in relation to the nonwoven substrate.

In particular, the filter for a smoking or vaping article produced bythe production process of the invention has a right circular cylindricalshape and comprises an outer envelope of plug wrap paper for a filterfor a smoking or vaping article and the nonwoven substrate of the filterof the invention as defined above located within the outer envelope.

The nonwoven substrate of the filter of the invention can therefore beobtained by a drylaid process.

The drylaid process and the airlaid process are two different theconventional routes known to the person skilled in the art to produce aweb. The person skilled in the art will know how to adapt the parametersof the drylaid process to produce the nonwoven substrate of the filterof the invention.

The process of the invention can comprise, if need be, before productionstep i), a step i1) of cutting the natural fibers to obtain naturalfibers having a length within the ranges mentioned above.

Cutting step i1) can be carried out by conventional techniques such asguillotine cutting, grinding of the natural fibers with or without asystem for removing excessively short and excessively long fibers of aircyclone or screen type.

During introduction step ii), an aqueous dispersion of the binder isintroduced into the web. This introduction may for example be carriedout by impregnation, such as impregnation with a size press, byspraying, such as spraying using a spray, by surface application, suchas surface application by coating or by printing, in particular byspraying a spray. Advantageously, the spraying will be performed on bothfaces of the web.

The aqueous dispersion of the binder can be obtained by any techniqueknown to the person skilled in the art. The person skilled in the artwill know how to adapt the concentration of binder in the aqueousdispersion to obtain the desired content of binder in the nonwovensubstrate of the filter of the invention.

Drying step iii) can, for example, be carried out by a drying device,such as a tunnel through which air passes or an infrared ramp.

This drying step iii) can be carried out at a temperature of between 75°C. and 200° C., in particular between 90° C. and 170° C., moreparticularly between 100° C. and 120° C. A temperature within theseranges advantageously makes it possible to minimize the duration of thisdrying step iii) while at the same time minimizing the deterioration ofthe natural fibers of the nonwoven substrate, thus optimizing theprocess of the invention.

Advantageously, the combination of the introduction step ii) and of thedrying step iii) makes it possible to improve the cohesion of thenatural fibers and hence to consolidate the structure of the nonwovensubstrate of the filter of the invention.

The natural fibers used in production step i) can be a mixture ofnatural fibers. This mixture of natural fibers can be obtained beforeproduction step i).

The natural fibers can be bast fibers which have undergone priortreatment, such as cottonized bast fibers, individualized bast fibers,bast fibers which have undergone retting and mixtures thereof, inparticular cottonized bast fibers, individualized bast fibers andmixtures thereof.

The process of the invention can thus comprise, before production stepi), a step i2) of treating the bast fibers chosen from retting,bleaching, cottonizing, individualizing, and a mixture thereof, inparticular cottonizing, individualizing or individualizing followed bycottonizing.

Cottonizing is a treatment in which the fibers are refined in order topass through cotton mills. The person skilled in the art knows how toimplement a cottonizing treatment step i2).

Individualizing is a treatment in which all or some of the fibers of aset of fibers are separated from one another. Individualizing can, forexample, be carried out by combing or by a chemical treatment.

This treatment step i2) may take place before, after or before and afteroptional cutting step i1).

For example, the bast fibers may undergo, optionally, individualizingtreatment step i2), cutting step i1) to obtain bast fibers having alength within the abovementioned ranges, then optionally cottonizingtreatment step i2), in particular cutting step i1) to obtain bast fibershaving a length within the abovementioned ranges, then cottonizingtreatment step i2).

The process may also comprise, between production step i) andintroduction step ii), a step ii1) of compacting the web to obtain acompacted web, this compacted web then undergoing introduction step ii).

This compacting step ii1) can make it possible to reduce the thicknessof the web in order to control the density of the nonwoven substrate.

According to another very particular embodiment, the process cancomprise the following steps:

i) producing a web by a drylaid process from a mixture of natural fiberscomprising between 85% and 95% of cottonized flax fibers by weight ofsolids of said mixture of fibers and between 5% and 15% of lyocellfibers by weight of solids of said mixture of fibers,

ii) introducing a binder chosen from starch, polyvinyl alcohol,ethylene-vinyl acetate or a mixture thereof into the web by spraying anaqueous dispersion of binder,

iii) drying the web resulting from step ii) to obtain a nonwovensubstrate which can have a density of between 10 mg/cm³ and 40 mg/cm³and in which the mixture of fibers can represent between 85% and 98% byweight of solids of said nonwoven substrate and binder can representbetween 2% and 15% by weight of solids of said nonwoven substrate.

Optionally, the nonwoven substrate obtained at step iii) may becalendered.

After step iii) and before step a), the nonwoven substrate may be packedas bobbin, as roll by a spooling process or in paperboard by afestooning process.

EXAMPLES Example 1: Manufacture of the Nonwoven Substrate

In the Examples, the air permeability is determined using “FX3300 LabAir IV” Air permeability tester. During the measurements, the tested webis placed under the measurement head and we measured the air flowpassing through the web at pressure drop of 200 Pa over the area of 20cm². The permeability is measured in [cm³/cm²/sec]. For each sample,three measurements were made and the indicated air permeability is theaverage value.

Example 1.1: Nonwoven Substrate Prepared by a Drylaid Process andComprising 95% by Weight of Solids of Said Nonwoven Substrate of aMixture of Cottonized Flax Fibers and of Lyocell Fibers (90% CottonizedFlax/10% Lyocell by Weight of Solids of the Mixture of Fibers) and 5% byWeight of Solids of Said Nonwoven Substrate of Starch

The cottonized flax fibers (VERVAEKE FIBRE NV, 22 mm in length) and thelyocell fibers (1.7 dtex/38 mm in length from Lenzig) were mixed, openedand parallelized with a card before being deposited on a forming fabric.A solution comprising 5% solids content of starch (Perfectafilm X115manufactured by Avebe) is sprayed onto both sides of the web. Thesprayed web is then dried by hot air oven at a temperature of between100° C. and 120° C. The content of binder in the web is 5%.

The nonwoven substrate obtained has a density of 11 mg/cm³, a thicknessof 4190 μm, a grammage of 47 g/m² and an air permeability of 650cm³·cm⁻²·sec⁻¹.

All the examples have the same fiber size, with an average length beforemanufacture of 22 mm for the cottonized flax fibers and of 38 mm for thelyocell fibers.

Example 1.2: Nonwoven Substrate Prepared by a Drylaid Process andComprising 95% by Weight of Solids of Said Nonwoven Substrate of aMixture of Cottonized Flax Fibers and of Lyocell Fibers (90% CottonizedFlax/10% Lyocell by Weight of Solids of the Mixture of Fibers) and 5% byWeight of Solids of Said Nonwoven Substrate of Starch

The nonwoven substrate is obtained by the process described in example1.1. After drying, the web was compacted at a pressure of 1 bar. Thecontent of binder in the web is 5%.

The nonwoven substrate obtained has a density of 22 mg/cm³, a thicknessof 1900 μm, a grammage of 42 g/m² and an air permeability of 640cm³·cm⁻²·sec⁻¹.

Example 1.3: Nonwoven Substrate Prepared by a Drylaid Process andComprising 88% by Weight of Solids of Said Nonwoven Substrate of aMixture of Cottonized Flax Fibers and of Lyocell Fibers (90% CottonizedFlax/10% Lyocell by Weight of Solids of the Mixture of Fibers) and 12%by Weight of Solids of Said Nonwoven Substrate of Starch

The nonwoven substrate is obtained by the process described in example1.1. The content of binder in the web is 12%.

The nonwoven substrate obtained has a density of 14 mg/cm³, a thicknessof 2040 μm, a grammage of 29 g/m² and an air permeability of 890cm³·cm⁻²·sec⁻¹.

Example 1.4: Nonwoven Substrate Prepared by a Drylaid Process andComprising 95% by Weight of Solids of Said Nonwoven Substrate of aMixture of Cottonized Flax Fibers and of Lyocell Fibers (90% CottonizedFlax/10% Lyocell by Weight of Solids of the Mixture of Fibers) and 5% byWeight of Solids of Said Nonwoven Substrate of Polyvinyl Alcohol

The nonwoven substrate is obtained by the process described in example1.1. A solution comprising 5% solids content of polyvinyl alcohol(Elvanol 71-30 manufactured by Kuraray) is sprayed onto both sides ofthe web. The content of binder in the web is 5%.

The nonwoven substrate obtained has a density of 17 mg/cm³, a thicknessof 2500 μm, a grammage of 43 g/m² and an air permeability of 800cm³·cm⁻²·sec⁻¹.

Example 1.5: Nonwoven Substrate Prepared by a Drylaid Process andComprising 85% by Weight of Solids of Said Nonwoven Substrate of LyocellFibers and 15% by Weight of Solids of Said Nonwoven Substrate of Starch

The nonwoven substrate is obtained by the process described in example1.1. The binder level in the web is 15%.

The non-woven substrate has a density of 13 mg/cm3, a thickness of 2690μm, a basis weight of 36 g/m² and an air permeability of 660cm³·cm⁻²·sec⁻¹.

Example 1.6: Nonwoven Substrate Prepared by a Drylaid Process andComprising 91% by Weight of Solids of Said Nonwoven Substrate ofCottonized Flax Fibers and Lyocell Fibers Mixture (90% CottonizedFlax/10% Lyocell by Weight of the Fiber Mixture) and 9% by Weight ofSolids of Said Nonwoven Substrate of Ethylene-Vinyl Acetate

The nonwoven substrate is obtained by the process described in example1.1. A solution comprising 3% of ethylene-vinyl acetate solids (®VinamulElite 15 manufactured by Celanese) was sprayed on both sides of the web.The content of binder in the web is 9%.

The non-woven substrate has a density of 22 mg/cm3, a thickness of 1600μm, a basis weight of 38 g/m² and an air permeability of 712cm³·cm⁻²·sec⁻¹.

Example 1.7: Nonwoven Substrate Prepared by a Drylaid Process andComprising 92% by Weight of Solids of Said Nonwoven Substrate ofCottonized Flax Fibers and Lyocell Fibers Mixture (90% CottonizedFlax/10% Lyocell by Weight of the Fiber Mixture) and 8% by Weight ofSolids of Said Nonwoven Substrate of Starch

The nonwoven substrate is obtained by the process described in example1.1. After the drying, the web was calendared with a pressure of 7 bar.The binder level in the web is 8%.

The non-woven web has a density of 44 mg/cm3, a thickness of 900 μm anda basis weight of 40 g/m².

Example 2: Manufacture and Characterization of Filters for a SmokingArticle

Filters for a smoking article were manufactured with the substrates ofexamples 1.1 to 1.7 by a standard method for manufacturing filterswithout passage through a crimping machine. A nonporous plug wrap paperwas used to wrap the rods of nonwoven filtering material.

The filters of the invention were compared with the paper filter andwith the commercial cellulose acetate filter. The paper filter was madeusing a standard method for manufacturing filters by crimping thesubstrate CF 36 of 36 g/m² and 100 μm thickness. The filters obtainedfor each term were cut into 21-mm sticks.

The characteristics of the filters are given in table 1 below.

Example 3: Manufacture and Characterization of Cigarettes

Cigarettes were prepared using the filters described in example 2. Toform the cigarettes, the rods of tobacco were assembled with the filtersusing tipping paper. A commercial “American blend” tobacco was used toform the rods of tobacco. The cigarettes were prepared with a pressuredifference similar to that of the commercial cigarette. The ventilationof the cigarettes was blocked.

The cigarettes prepared were smoked on a Borgwaldt RM20 smoking machinein accordance with the standard ISO 3308:2000. The pressure drop (PD intable 2) was measured in accordance with the standard ISO 6565:2002. Thenicotine content in the smoke was measured in accordance with thestandard ISO 10315:2000. The smoking results are given in table 2 below.

Table 2 demonstrates that, with an equivalent pressure drop, thecigarettes with filters according to the invention and the cigarettescomprising a commercial cellulose acetate filter have a nicotine contentin the smoke which is of the same order of magnitude, whereas thecigarettes comprising a filter made from crimped paper have a much lowernicotine content in the smoke.

This example 3 thus demonstrates that the user experience provided bythe cigarettes comprising the filters comprising the substrate accordingto the invention is as satisfactory as that provided by cigarettescomprising a commercial cellulose acetate filter.

TABLE 1 Filter Filter Filter Filter Filter Filter Filter Commercialcomprising comprising comprising comprising comprising comprisingcomprising Filter cellulose the substrate the substrate the substratethe substrate the substrate the substrate the substrate made fromacetate of of of of of of of crimped CF36 filter example 1-1 example 1-2example 1-3 example 1-4 example 1-5 example 1-6 example 1-7 paper Lengthof the 21 filters [mm] Diameter of the 7.8 filters [mm] Weight of the139 ± 5 115 ± 1 134 ± 1 155 ± 1 147 ± 1 149 ± 1 154 ± 1 157 ± 5 221 ± 1filters [mg] Density of the 138 117 137 159 150 150 150 151 226 filters[mg/cm³]

TABLE 2 Filter Filter Filter Filter Filter Filter Filter Commercialcomprising comprising comprising comprising comprising comprisingcomprising Filter cellulose the substrate the substrate the substratethe substrate the substrate the substrate the substrate made fromacetate of of of of of of of crimped CF36 filter example 1-1 example 1-2example 1-3 example 1-4 example 1-5 example 1-6 example 1-7 paper Numberof 30 cigarettes smoked PD of the 104 ± 1  90 ± 1  93 ± 1  91 ± 1  100 ±1  107 ± 1  103 ± 1  96 ± 5  100 ± 1   cigarettes [mmWC] Nicotine 0.85 ±0.04 0.85 ± 0.04 0.71 ± 0.05 0.78 ± 0.05 0.78 ± 0.05 0.71 ± 0.04 0.70 ±0.03 0.71 ± 0.07 0.5 ± 0.19 [mg/cigarette]

1. Filter comprising a nonwoven substrate comprising natural fibers anda binder, in which the natural fibers represent between 70% and 99% byweight of solids of said nonwoven substrate, the binder representsbetween 1% and 30% by weight of solids of said nonwoven substrate,characterized in that the nonwoven substrate has a density of between 7mg/cm3 and 60 mg/cm3.
 2. Filter according to claim 1, in which thenonwoven substrate has a thickness of between 700 μm and 6000 μm. 3.Filter according to claim 1, in which the length of the natural fibersis greater than 10 mm and less than or equal to 150 mm.
 4. Filteraccording to claim 1, in which the natural fibers are chosen from woodfibers, leaf fibers, fruit fibers, seed fibers, bast fibers, stalkfibers, reed fibers and mixtures thereof.
 5. Filter according to claim4, in which the wood fibers are chosen from lyocell fibers, viscosefibers, and mixtures thereof.
 6. Filter according to claim 4, in whichthe bast fibers are chosen from hemp fiber, Indian hemp fiber, jutefiber, kenaf fiber, kudzu fiber, flax fiber, okra fiber, nettle fiber,ramie fiber, and mixtures thereof.
 7. Filter according to claim 1, inwhich the binder is a synthetic polymer or copolymer.
 8. Filteraccording to claim 1, in which the binder is chosen from apolysaccharide, preferably starch, a cellulose derivative, and mixturesthereof.
 9. Filter according to claim 1, in which the binder is apolyvinyl alcohol, a polyvinyl acetate, or an ethylene-vinyl acetate.10. Filter as defined in claim 1 for smoking article or vaping article.11. Smoking article comprising a filter as defined in claim
 1. 12.Vaping article comprising a filter as defined in claim
 1. 13. Processfor producing a filter for a smoking or vaping article comprising anonwoven substrate, said process comprising the following steps: a)forming a rod of nonwoven substrate from a nonwoven substrate, b)wrapping the rod of nonwoven substrate with a sheet of plug wrap paper,c) depositing an adhesive line, joining the sheet of plug wrap paper toobtain a rod of filtering material, d) cutting the rod of filteringmaterial to produce the filter, wherein the nonwoven substrate is asdefined in claim 1 or is obtained by a process comprising the followingsteps: i) producing a web from natural fibers by a drylaid process, ii)introducing the binder into the web, and iii) drying the web resultingfrom step ii) to obtain the nonwoven substrate.
 14. Process according toclaim 13 in which, after step iii) and before step a), the nonwovensubstrate is packed as bobbin, as roll by the spooling process or inpaperboard by the festooning process.